66 Davis . — The Fertilization of Batrachospermum . 
frequently occupies a position farthest away from the point 
of fusion (see Figs. 24, 25, and 28). It will be noticed from 
the figures that the point of fusion is at first very small, and 
it sometimes remains so for a long time, although as a rule it 
gradually widens. However, the process of widening takes 
place particularly slowly in this species, and the tendency 
on the part of the nucleus of the antherozoid to pass into 
the trichogyne is much less noticeable than in B. monilifonne . 
In fact, cases in which the nucleus of the antherozoid had left 
that organ, as in Fig. 26, were rather infrequent. We must: 
make special mention of one very interesting specimen 
(Fig. 27). Here there was no nucleus in the trichogyne 
proper ; but just inside the antherozoid, near the point where 
the two structures were united, was one nucleus, and a second 
lay in the antherozoid at the side farthest away from the 
point of fusion. Apparently the nucleus of the trichogyne 
originally lay near the tip of that structure, as in Fig. 25, and 
when fusion took place the movement of the cytoplasm was 
into the antherozoid, and the surge carried the nucleus of the 
trichogyne with it. Certain appearances of the protoplasm 
around the nucleus of the trichogyne tended to support this 
explanation. 
Although more than one antherozoid maybe frequently found 
clinging to the trichogyne, as in Fig. 28, only one ever fuses, 
and this plant was particularly favourable for the study of this 
point. Specimens were occasionally observed in which anthero- 
zoids were attached to the base of the trichogyne (Fig. 29), 
but there never appeared to be protoplasmic fusion under such 
conditions. 
The interesting phenomenon of nuclear fragmentation is 
very characteristic of this species. The process does not, 
as a rule, begin until the trichogyne is cut off from the 
carpogonium as an independent cell. However, in the 
example shown in Fig. 23, a specimen in which the tricho- 
gyne was still united to the carpogonium, the nucleus of the 
trichogyne was very large and irregularly elliptical in its out- 
line, as though it were about to divide. Two fragments of the 
